One of the reasons that the 70+ 360/390/401s ran so good is that AMC disected the competition's engines and equaled or improved almost every aspect. (oil system is a bit weak, OK under 6500RPMs)
The unported "Dogleg" heads flow only slightly less than the early hemi heads, and OUTFLOW the early HEMI heads when ported!!!
The fully ported Indy SR-1 heads are maybe even a lil weaker than the genuine 291c.
Check out the flow chart from Indy:
http://www.american-powersports.com/dave/image/amx/tech/head_flow.htm
AMC also used 1" wrist pins, super high nickel in their cast iron (no 4-bolt mains required), and bulletproof forged crank and rods.
Their design at the timing chain cover area lends itself very well to NASCAR and NHRA, all that stuff can come rite off. Install a dry sump, crank trigger ign, external water pump, etc.
Way ahead of their time, squashed by the Arabs!